[Association between smoking and tuberculosis infection].

PURPOSE: Several reports show smoking as a risk factor of tuberculosis (TB) infection, especially in prisoners, emigrants, the homeless, or people in areas where TB is endemic. These reports mostly used the tuberculin test to detect TB. However, there is no report evaluating smoking as a risk factor of TB infection among people coming into contact with TB with the use of the Interferon-Gamma Release Assays (IGRA) test. MATERIAL & METHOD: We compared TB infection in smokers and non-smokers who came into contact with TB infection by using the IGRA test. We retrospectively collected information about people coming into contact with TB who visited the Daiichi Dispensary from July 1, 2011 to June 30, 2012. They were divided into 2 groups (IGRA positive or negative) and smoking (present/past or never). RESULT: Out of 390 subjects who came into contact with TB examined, 229 were male and 161 were female. The mean age was 39.0 years, 98 were present smokers, 69 were past smokers, and 223 were never-smokers. There were 19 IGRA-positive and 371 IGRA-negative subjects. The IGRA positive rate was 4.9%. Out of 19 IGRA-positive subjects, 13 were smokers or ever-smoker (68.4%). Out of 371 IGRA-negative subjects, 154 cases were smoker or ever-smoker (41.5%). Smoking experience (present and past) was statistically significant in the IGRA-positive group. There were no significant differences in sex, age, drinking habits, and level of contact. Multivariate analysis showed smoking was only one independent risk factor for being IGRA-positive (odds ratio 3.06, 95% confidence interval: 1.14-8.21, p = 0.027). DISCUSSION: Our results suggest that smoking experience in subjects coming into contact with TB is a risk factor for TB infection. TB cases in smokers are reported to be more severe and have delayed detection of disease. They are also more likely to infect those who come in contact with them. If TB source cases and their contacts are both smokers and co-exist in a narrow and limited area, the contacts might be at higher risk of exposure to TB-contaminated air than non-smokers.

[Liver dysfunction during treatment of latent tuberculosis infection].

PURPOSE: The indications for treatment for latent tuberculosis infection were revised in 2007 to reflect that any subject with a higher risk of tuberculosis regardless of age should be treated. We worried about the incidence of liver dysfunction due to isoniazid (INH) in patients older than 30 yrs. of age. We evaluated the frequency of liver dysfunction due to INH according to age and discussed the possibility of its prevention. METHODS: We reviewed the clinical records of 99 patients younger than 29 yrs. and 229 patients older than 30 yrs. who were treated for latent tuberculosis infection from August 2007 to December 2008 at our clinic. The liver function tests (AST and ALT) were performed before the treatment, one and a half months after the start of the treatment, and almost every month during the treatment. We defined liver dysfunction as an AST and/or ALT greater than 100 IU/L. RESULTS: Seven out of the 99 younger patients (7.1%) and 42 out of the 229 (18.3%) older patients developed liver dysfunction. The difference between the two age groups was statistically significant according to the chi-square test (p < 0.01). After the occurrence of liver dysfunction, 35 out of 49 patients (71%) completed the treatment by maintaining the same or a decreased dose of INH, while the medication was discontinued in 9 patients who were then followed up by chest X-ray examination. Two of these 49 patients discontinued the medication by themselves. CONCLUSIONS: The frequency of liver damage due to INH was higher in persons older than 30 yrs. In this group, 3 persons developed severe liver damage with ALT and/or AST higher than 1000 IU/L. Early detection is required to avoid serious damage. Thus, we decided to perform liver function tests more often, i.e., at 2 weeks after the onset of treatment and every month thereafter.